By Michael Holden
LONDON (Reuters) - The European Union puts British families at risk by allowing the free movement of dangerous criminals, campaigners who want Britain to leave the bloc said on Tuesday, an argument dismissed as "scaremongering of the worst kind" by EU supporters.
Polls show that concerns about migration and border controls are likely to play a big role in how Britons will vote in a referendum on June 23 on Britain's EU membership.
The Vote Leave campaign, one of the groups pushing for an exit, compiled a dossier listing people who it described as the 50 most dangerous citizens from EU countries in Britain and who committed offences including murder and rape in the country.
EU laws meant states within the bloc did not have to inform British authorities on a systematic basis about the criminal backgrounds of their nationals allowing free movement for dangerous individuals, it said.
"EU membership means we have lost control of our borders and have been unable to prevent dangerous individuals from walking into the UK," Vote Leave Chief Executive Matthew Elliott said.
"Free movement of people has created free movement of criminals making the UK less safe and less secure."
Lucy Thomas, deputy director of the Britain Stronger In Europe group, described the argument as "scaremongering of the worst kind."
"It is a mix of chaos and confusion," said Conservative lawmaker Damian Green, a former interior ministry minister who backs staying in the EU.
"The truth is that the UK already has the best of both worlds. We maintain all the benefits of EU membership whilst opting out of the passport-free Schengen area and maintaining our border at Calais (in France) rather than at Dover."
In the last few days, campaigners on both sides have traded claims and counter-claims about whether a British exit from the EU would be damaging for Britain on issues ranging from security to the national health service.
Education Secretary Nicky Morgan said on Monday that young people could become a "lost generation" if Britain left and firms were suspending hiring decisions or advertising jobs.
Vote Leave said the EU had been bad for the young by driving up costs and forcing down wages.
"In" campaigners are keen to mobilise younger voters who surveys show are overwhelmingly pro-EU but also less likely to bother voting.
(Editing by William Schomberg)